In his U.S. Pat. No. 5,967,700, issued Oct. 19, 1999 the applicant herein discloses apparatus and method to form an in-situ piling in existing soil. This patent is incorporated herein by reference in its entirety for its showing of apparatus to inject water and binder (such as cement and/or lime) into a soil structure, and for related methods. The apparatus mixes these materials, and after a time the mixtures solidifies to form the pilings. One object of the apparatus and method was to provide a suitable mixture at appropriate depths. Much of its advantage was the assurance that the stoichiometric amount of water was provided to react with the binder to make a cured product of suitable strength.
This procedure works well in all soils, but in clay soils it becomes of interest that surprisingly improved results can be attained. With the instant invention, they have been. Increased structural properties, reduced cost of binder, decreased cost of labor and capital equipment, increased speed of installation, and reduction of power to prepare the piling have been extraordinary and were not predicted. These results are principally achieved in clay soils. They are less likely and important in sandy or aggregate soils, although still worth while.
A clay soil is a rather “tough” structure—neither hard nor fluid, but sticky and unwieldy. It is difficult to cut through or to knead. In a word, it lacks “fluidity”. This property leads to the problem of providing a piling that is suitably uniform in its composition. Known in-situ pilings often result in structures with sinews of cement surrounded by parent material. This does not form an optimal supportive structure.
Another problem in the prior art is the fact that after water and binder are mixed in, the top of the piling ends up far below the surface. Then there is a hole to be filled in, at considerable cost and aggravation.
Applicant herein has found that a sufficiently fluid in-situ mixture of parent clay, binder, water, and to a fugatious extent, air, can provide the consistency for a very suitable in-situ piling. Surprisingly, when so provided, a wide range of binder concentrations and process water can be accommodated, and surprisingly rapid first and final strengths are attained, all with a nearly homogenous consistently lateral cross section.